Patriot Coal is suspending output for two weeks at its mine in Boone County, West Virginia, US, after a roof collapsed.
The company said the accident could impact the mine's second-quarter earnings.
In a statement, Patriot Coal said the roof at the Harris No 1 mine in Patriot's Rocklick complex fell on June 12 and that there were no injuries.
The mine's production had already been affected after it was shut because of ventilation problems by the US Mine Safety & Health Administration.
The Harris mine produces about 620,000t of coal a year.